Let them touch and hold books while you point to and name the pictures.
Use real words instead of baby talk - "give me" instead of ta ta or "water" instead of wawa.
Take the time to listen to them - they want you to hear all of their new sounds, words and ideas.
Give them simple directions to follow - "Go find your red boots".
Use lots of different words when you talk to them - opposite words like up/down, in/out; action words like "running", "splashing", and descriptive words like "happy", "big", "little", "clean", "dirty".
Encourage them to play with other children - at the library, play groups, park.